CN104010739A - Coating composition and coated paper and coated paperboard - Google Patents

Abstract

A coating composition may include kaolin having a shape factor less than about 70 and calcium carbonate, wherein less than about 90% by weight and greater than about 60% by weight of particles of the calcium carbonate have an equivalent spherical diameter (esd) less than 2 microns. The coating composition may include a thickener present in an amount ranging from about 0.1 % to about 0.9% by active dry weight of the composition. A coating composition may include kaolin having a shape factor less than about 70 and calcium carbonate having a mean particle size (d50) of at least about 2.4 microns and a steepness factor of at least about 30. The coating composition may be a paper basecoat composition or a paperboard basecoat composition. A paper or paperboard product may include the coating composition on at least one surface of the paper product or paperboard product.

Description

Coating composition and coated paper and coated board

claim of priority

The benefit of priority of the U.S. Provisional Application No. 61/715,628 that this PCT international application requires to submit on March 15th, 2013 U.S. Provisional Application No. submits on October 18th, 61/787,222 and 2012, both themes are all incorporated to herein as a reference.

open field

The disclosure relates to coating composition, relates more specifically to the coating composition for paper and board product.

open background

Can on base material, apply coating to strengthen physics and the optical property of base material.For example, in printing and processing (converting) industry, paper and cardboard used may stand various operations, for example, print, cutting, impression, folding and/or gluing.Coated board is widely used in packaging industry, and typical formulation for coating material can comprise one or more pigment, adhesive and additive.This type of coating can be used for improving physics, optics and/or the barrier property of product.Physics and/or the optical property packaging that this coated substrate forms of can serving as reasons provides aesthstic attractive force and/or function benefit.Paper and board product may be very responsive to moisture and moisture, and barrier property can provide the obstruct to moisture, oil, water vapour or gas.

Impression and folding operation are the significant process in processing industry.But impression may cause Paper or cardboard base material to apply sizable strain with folding.The mechanical strength of any coating existing on such strain challenge base material and base material.For example, the brisement occurring at impression and the folded edge of paper and board product may significantly weaken the barrier property of base material and may reduce the overall aesthstic attractive force of the packaging being formed by this base material.Cannot bear these large strains and may cause folded edge brisement, thereby may cause large coating crack or peel off or the two.

Traditionally, the coating with high-stiffness is preferred, because the coating of higher stiffness can provide excellent intensity and/or reduce the fiber consumption in base material.But the coating of higher stiffness may tend to improve the cracking occurring at the folded edge of Paper or cardboard or the order of severity of peeling off.

Therefore, may be desirable to provide the coating composition that shows improved cracking resistance and/or spalling or show improved performance in the time scribbling the base material folded of this coating composition in the time that base material stands printing or process operation.

general introduction

According to first aspect, coating composition can comprise kaolin and the calcium carbonate with the form factor that is less than about 70, is wherein less than about 90 % by weight and has the equivalent spherical diameter (esd) that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

" form factor " used herein is to granularity and variform particle swarm, use for example U.S. Patent No. 5, conductivity method described in 128,606 and device and use particle mean size that the equation of deriving in its description records and the tolerance of the ratio average (based on weight average) of grain thickness." particle mean size " is defined as the diameter of a circle with the area identical with the largest face of particle.Make the waterborne suspension (electrical conductivity) of the abundant dispersion of the tested particle elongated tubular of flowing through.Along the spaced-apart pair of electrodes of the longitudinal axis of this pipe, and (b) cross over the measurement of carrying out electrical conductivity between the spaced-apart pair of electrodes of the transverse width of this pipe at (a).Use the difference of these two conductivity measurements to measure the form factor of tested microparticle material.

" granularity " used herein, for example, in the situation of size distribution (psd), can measure by equivalent spherical diameter (esd).The particle mean size of mentioning in the disclosure and other granularity character---be sometimes called " d ₅₀" value, can measure with known manner, for example, by using SEDIGRAPH 5100 instruments of Micromeritics Corporation supply, make the microparticle material sedimentation under abundant dispersity in aqueous medium.This instrument can provide measurement result and granularity (being known as in the art " equivalent spherical diameter " (esd)) to be less than the curve of the cumulative weight percentage of the particle of given esd value.For example, particle mean size d ₅₀the particle esd value that can measure thus---wherein the particle of 50 % by weight has and is less than this d ₅₀the esd of value.

According on the other hand, this coating composition can comprise thickener.For example, thickener can be in by the amount of said composition active material dry weight about 0.1% to about 0.9%, by the amount of said composition active material dry weight about 0.2% to about 0.6%, exist by the amount of said composition active material dry weight about 0.4% to about 0.9% or by the amount of said composition active material dry weight about 0.4% to about 0.6%.According on the other hand, thickener can be selected from alkali-soluble emulsion polyacrylic ester thickener and the CMC(carboxymethyl cellulose of alkali-soluble emulsion polyacrylic ester thickener, hydrophobically modified) thickener.

According to more on the one hand, the kaolin that is less than about 30 % by weight has the esd that is less than about 0.25 micron.For example, the kaolin that is less than about 25 % by weight has the kaolin that is less than the esd of about 0.25 micron or is less than about 20 % by weight and has the esd that is less than about 0.25 micron.

According to more on the one hand, kaolin has the particle mean size (d that is less than about 1 micron ₅₀).According on the other hand, the kaolin that is less than about 80 % by weight has the esd that is less than about 1 micron.According to more on the one hand, the kaolin that is less than about 90 % by weight has the esd that is less than about 2 microns.

According to more on the one hand, be less than about 80 % by weight and there is the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.For example, be less than about 70 % by weight and there is the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

According to more on the one hand, this coating composition is paper substrates coating composition or cardboard substrate coating composition.According to more on the one hand, paper product or board product can comprise coating composition at least one surface of this paper product or board product, wherein this coating composition comprises kaolin and the calcium carbonate with the form factor that is less than about 70, is wherein less than about 90 % by weight and has the equivalent spherical diameter (esd) that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

According on the other hand, coating composition can comprise having the kaolin of the form factor that is less than about 70 and have the d of at least about 2.4 microns ₅₀the calcium carbonate of at least about 30 steepness coefficient (steepness factor).

The size distribution (psd) of microparticle material also can characterize by " steepness " or " steepness coefficient ".Steepness coefficient is derived by psd slope of a curve, and the accumulative total mass percent that wherein particle diameter is plotted in vs particle on x-axle is plotted on y-axle.Wide size distribution has relatively low steepness coefficient, and narrow size distribution produces relatively high steepness coefficient.In certain aspects, steepness coefficient can be used as following ratio calculating:

The accumulative total quality of, measuring by Sedigraph 5100 is less than the granularity (d of 30% particle ₃₀) be less than the granularity (d of 70% particle with accumulative total quality ₇₀) ratio, be multiplied by 100.Along with d ₃₀and d ₇₀be worth near each other, steepness coefficient improve.

According to more on the one hand, the particle mean size (d of calcium carbonate ₅₀) can be greater than about 2.6 microns, be greater than about 2.8 microns, or be greater than about 3.0 microns.According to more on the one hand, steepness coefficient (for example d of calcium carbonate ₃₀/ d ₇₀x100) can be greater than approximately 32, be greater than approximately 34, be greater than approximately 36, be greater than approximately 40, or be greater than about 43.

It being understood that general introduction and as detailed below are above only exemplary and explanatory and do not limit the present invention.

The accompanying drawing of a part that is incorporated to this description and form this description is for explaining at least some principles of the present invention.

accompanying drawing summary

Fig. 1 is the schematic diagram at the beam of its end support;

Fig. 2 is the figure that shows the elastic modelling quantity of coated sample;

Fig. 3 is the figure that shows the elastic modelling quantity of coated board sample;

Fig. 4 is the figure that shows the bending break stiffness of coated board sample;

Fig. 5 is the figure that shows the elastic modelling quantity of coated board sample;

Fig. 6 is the figure that shows the bending break stiffness of coated board sample;

Fig. 7 is the figure that peels off grade (flaking ratings) that shows coated board sample;

Fig. 8 is the cracking grade that shows coated board sample;

Fig. 9 shows to peel off and the figure of the grade vs. amount of thickener that ftractures;

Figure 10 is the figure that shows bending break stiffness vs. amount of thickener;

Figure 11 shows the figure that peels off grade vs. base coating weight;

Figure 12 shows cracking grade vs. base coating weight;

Figure 13 is the figure that peels off grade and flexural modulus results that shows Coating material composition matter sample;

Figure 14 shows the cracking grade of Coating material composition matter sample and the figure of flexural modulus results;

Figure 15 is the figure that peels off grade and bending break stiffness result that shows Coating material composition matter sample;

Figure 16 shows the cracking grade of Coating material composition matter sample and the figure of bending break stiffness result;

Figure 17 is the figure that shows the folding property vs. roughness result of Coating material composition matter sample;

Figure 18 is the figure that shows the bending break stiffness result of Coating material composition matter sample;

Figure 19 is the figure that shows bulk (bulk) the vs. composition of Coating material composition matter sample; And

Figure 20 is the figure that shows the mercury injection method to Coating material composition matter sample.

exemplary is described

Now in detail with reference to exemplary of the present invention.

Applicant determines surprisingly, can peel off and/or ftracture with the folding line of coated paper product and board product links together by comprising that the coating composition of combination of kaolin and calcium carbonate reduces sometimes.For example, the coating composition of---be wherein less than about 90 % by weight and have the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight---can make with the paper product of this coating composition coating or the reduction of peeling off and/or ftracture at board product folding line place to comprise kaolin and the calcium carbonate with the form factor that is less than about 70.

According to some embodiments, this coating composition can comprise thickener, for example the thickener to exist by said composition active material dry weight about 0.1% to about 0.9% amount.For example, thickener can be selected from alkali-soluble emulsion polyacrylic ester thickener and the CMC(carboxymethyl cellulose of alkali-soluble emulsion polyacrylic ester thickener, hydrophobically modified) at least one in thickener.

Do not wish to be subject to theory, but believe, can be caused the modulus of improvement of this coating and (reducing) this coating of deflection and improvement peeling off and/or ftractureing paper and board product folding line place by the interstitital texture of the coating providing according to the coating composition of at least some embodiments disclosed herein.Believe especially, surprisingly, in this coating composition, the roughness of kaolinic form factor, calcium carbonate and/or the amount of thickener are improved modulus and the deflection of coated paper or board product and are improved peeling off and ftractureing of coated product folding line place.For example, having the tabular kaolin of the form factor that is less than 70 and size distribution is the peeling off and/or ftractureing at coated product folding line place that is less than the GCC particle of about 90 % by weight and the modulus of coated product and the improvement of deflection and improvement are provided more than the grinding calcium carbonate (GCC) that the GCC particle of about 60 % by weight has an esd that is less than 2 microns." tabular kaolin " used herein refers to the kaolin with high form factor.The peeling off and/or ftractureing at coated product folding line place of the modulus of coated product and the improvement of deflection and improvement is provided in the thickener existing by this Coating material composition active substances dry weight about 0.1% to amount of about 0.9% in addition.Can select independently of one another the granularity of kaolinic form factor, calcium carbonate and the amount of thickener to improve modulus and deflection and the peeling off and/or ftractureing at coated product folding line place of coated product.Or, can the kaolinic form factor of comprehensive selection, the granularity of calcium carbonate and the amount of thickener to be to improve modulus and deflection and the peeling off and/or ftractureing at coated product folding line place of coated product.

According to some embodiments, can be by for example processing the unprocessed microgranular hydrous kaolin mineral of appositional pattern, the kaolin clay undressed or part processing of the type that for example Georgia State, USA exists is manufactured kaolin.The kaolinic psd of processing makes at least 80 % by weight, and preferably the particle of at least 84 % by weight has and is less than 2 microns of (μ esd m).In certain embodiments, this kaolinic psd makes to be no less than the particle of 12 % by weight, and preferably 15% to 35%, especially 18% to 26% has the esd that is less than 0.25 micron.Desirably, at least 60%, preferably at least 65 % by weight have the esd that is less than 1 micron.Average grain esd can be 0.3 micron to 0.8 micron, especially 0.5 micron to 0.7 micron.

According to some embodiments, the percentage by weight of the kaolin particle with the esd of 0.75 micron to 0.25 micron of pigment product is according to a first aspect of the invention 40% or larger, for example 40% to 50%.The kaolinic form factor of processing can be at least 10, desirably at least 20, and for example about 10 to about 70, or about 20 to about 70, or about 30 to about 70, or about 40 to about 70, about 50 to about 70, or about 60 to about 70.

According to some embodiments, unprocessed microgranular hydrous kaolin can produce Kaolin pigments according to the illustrative methods processing comprising the following steps: (a) kaolin clay undressed or part processing is mixed to form waterborne suspension with water; (b), by the average shape factor of kaolin clay is improved at least 10, preferably at least 20 method is used particulate abrasive media to impose abrasion to the suspension of making by step (a); (c) suspension that grinds kaolin clay is separated with particulate abrasive media; (d) by classification, for example use centrifuge, obtain coarse grain component, with (e), the suspension of the thick kaolin clay grinding separating in step (c) is dewatered therefrom to reclaim Kaolin pigments.

According to some embodiments, in step (a), kaolin clay can form 20% to 70% of the suspension of processing, and for example 20% to 45%.Kaolin clay can comprise sedimentary kaolin clay, for example, from the sedimentary kaolin clay of Georgia State, USA.The psd of unprocessed kaolin clay can make no more than about 40 % by weight be greater than the particle of 10 microns by esd to form, and no more than 50 % by weight, and for example about 20% is less than the particle of 2 microns to about 40 % by weight by esd and forms.The form factor of kaolin clay of processing in step (a) may be less than 15, and for example about 5 to about 10.Therefore, form factor can be improved at least 30, for example at least 40 difference, for example, bring up to and be greater than 55 form factor (for example about 60 or larger to the form factor that is less than about 70) from being less than 15 form factor.

When prepare the waterborne suspension of the kaolin clay of processing in step (a) time, according to some embodiments, can in this kaolin clay, add or not add kaolin clay dispersant.

According to the kaolin clay of processing in the step of the method for some embodiments (a) can being the coarse grain component for example, being obtained by the classification (using centrifuge) of the block sedimentary kaolin clay of standard for example with about 5 to about 10 form factor.In this coarse grain component, the particle of no more than 50 % by weight has and is less than esd and no more than 10 % by weight of 2 microns and has the esd that is less than 0.25 micron.

According to some embodiments, can pass through about 99 kaolin clays to about 50 weight portions and about 1 to about 50 weight portions, the thin tabular kaolin component of for example 10 to 30 weight portions (particularly have at least about 15, for example about 15 to about 40 form factor and the percentage by weight that is wherein less than the particle of 2 microns and 0.25 micron are respectively the thin tabular component of at least about 85 % by weight and at least about 20 % by weight) blend regulates the psd of kaolin clay.This thin tabular kaolin component can be the kaolin derived from primary or sedimentary deposit.According to some embodiments, can before or after grinding steps (b), exemplary thin tabular kaolin component be added in the kaolin of this coarse grain component or the kaolin by this coarse grain component acquisition.Can carry out these the two kinds interpolations of wanting the kaolin component of blend with powdery dried forms or with the form of waterborne suspension.

Determine, manufacture kaolin product by blend in this way, improve according to rheological characteristic and the dehydration characteristic of the kaolinic waterborne suspension of some exemplary processing, for example, while using kaolin in coating composition, provide improved mobility and particle to arrange.

According to some embodiments, for example, can impose one or more known purification step to remove unacceptable impurity to kaolin clay in step (a) with (b).For example, can impose froth flotation to the waterborne suspension of kaolin clay and process operation with the titaniferous impurity except in defoaming.Or or in addition, can make this suspension process high strength magnetic separtor to remove ferrous contaminants.

According to some embodiments, step (b) can comprise the process of suspension that is ground (medium attrition grinding) and processed kaolin clay by abrasion medium, for example wherein about 40 kWh to the energy dissipation of about 250 kWh/ ton clays (based on dry weight) in this suspension.According to some embodiments, step (b) can comprise the process with at least two stages, for example, in the first stage (b1), delaminating of kaolin clay occurs, in second stage (b2), carry out the pulverizing of kaolin clay thin slice.

Have been found that, it is useful that the suspension of kaolin clay is imposed to relatively gentle pulverising step (b1), the composite particles (composite particles) that for example uses particulate abrasive media to grind to decompose to exist in undressed kaolin clay.Such composite particles generally includes independently cohesion lamination or the piece (blocks) of the tabular particle of hexagon, particularly when this kaolin clay is during from sedimentary deposit.When this kaolin clay is imposed to relatively gentle pulverizing (for example, by grinding) in step (b1) time, composite particles decomposes to provide independently basic hexagon thin plate.This process is commonly referred to as " delaminating " and has the result of the average shape factor that improves kaolin clay.For example, this example process can be brought up to the original shape factor of the form factor of kaolin clay from about 5 to about 10 at least about 50 to 55(for example about 60 to being less than about 70) the form factor of raising." gentle grinding relatively " used herein refers in grater (attrition grinding mill) and grinds with particulate abrasive media, stir the content of this grater by impeller, described impeller is to be enough to form the speed of eddy current in suspension, particularly with the peripheral speed rotation lower than about 10 meter per seconds, and the energy being wherein dissipated in process of lapping in this suspension is less than about 75 kWh/ tons, for example, be less than the kaolin clay (based on dry weight) of about 55 kWh/ tons.This particulate abrasive media can have relatively high proportion, and for example 2 or larger, and can for example comprise quartz sand crystal grain, wherein this crystal grain conventionally has and is not more than about 2 millimeters and be not less than the diameter of about 0.25 millimeter.

According to some embodiments, the stage (b2) of the step (b) of the two stage forms of the method---grind, can in the grater of being furnished with agitator, carry out, described agitator can be to form the speed rotation of eddy current in process of lapping in this grinding machine in suspension.This particulate abrasive media can have 2 or larger proportion can comprise quartz sand crystal grain, and wherein this crystal grain conventionally has and is not more than about 2 millimeters and be not less than the diameter of about 0.25 millimeter.If there is before the relatively gentle pulverizing in the stage (b1) in the stage (b2), the energy being dissipated in the stage (b2) in this kaolin clay suspension can be for about 40 kWh be to about 120 kWh/ ton dried kaolin clays.But if omit relatively gentle pulverising step (b1), the energy being dissipated in step (b) in this kaolin clay suspension is preferably about 100 kWh to about 250 kWh/ ton dried kaolin clays.

According to some embodiments of step (c), can in a known way the suspension that grinds kaolin clay be separated with particulate abrasive media, for example by making this suspension through thering is the sieve of suitable aperture size, for example, there is the sieve of the normal pore size size of about 0.1 millimeter to about 0.25 millimeter.

According to some embodiments of step (d), can use centrifuge (for example Alfa Laval or Merco) to grind the suspension classification of kaolin clay.

After step (c), step (d) or step (e), according to some embodiments, can further process kaolin clay to improve its one or more character.For example can apply for example energized fluid processing (for example using super mixer) to the product of slurry form afterwards before or in step (e) in step (e), be dispersed in again subsequently in aqueous medium, for example, in changing of coating composition little (makedown) process.

According to some embodiments, in step (e), can be in one of mode as known in the art, for example by filtering, centrifugal, evaporation etc. will grind kaolinic suspension dehydration.For example, can use filter press to there is the filter cake of about 15 % by weight to the water content of about 35 % by weight to form.Can, by this filter cake and kaolin clay dispersant, change into thus fluid slurry, it can and be sold with this form transport.Or kaolin clay can heated drying, for example, by the fluid slurry of kaolin clay is introduced to spray dryer, thus with the form transport of substantially dry.

According to some embodiments, this kaolin product has at least 12 meters squared per gram (m ²/ g), for example 15 m ²/ g to 20 m ²/ g passes through BET, N ₂the specific area that method records.

According to some embodiment, be less than about 80 % by weight and there is the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.For example, be less than about 70 % by weight and there is the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.Average grain esd can be 1 micron to 3 microns, especially 1 micron to 1.35 microns.

Particulate calcium carbonate used in certain embodiments of the present invention can maybe can synthesize preparation by precipitation available from natural resources by grinding, be winnofil (PCC), can be maybe both combinations, i.e. the mixture of natural derivative grinding-material and synthetic deposited material.Also can grind PCC.

Grinding calcium carbonate (GCC), conventionally by grinding mineral source, as chalk, marble or lime stone obtain, after this can be followed grading step, to obtain the product with required fineness.Can for example wear away and spontaneous abrasive particles solid material by the abrasion between the particle of solid material itself or under the particulate abrasive media of the particle that comprises the material different from the calcium carbonate grinding exists.

The wet-milling of calcium carbonate relates to the waterborne suspension that forms calcium carbonate, and it is optional at suitable dispersant subsequently, and for example Sodium Polyacrylate exists lower grinding.About the more information of the wet-milling of calcium carbonate, can reference example as EP-A-614948.Dispersant for grinding calcium carbonate can comprise non-ionic dispersing agent, substantially be made up of non-ionic dispersing agent or be made up of non-ionic dispersing agent.

After grinding, this suspension can be dehydrated into high solids content suspension, and remove any abrasive media.The high solids content suspension forming by described dehydration has at least about 10 % by weight (for example at least about 50 % by weight) suitably to about 80 % by weight, for example the solid content of maximum about 78 % by weight.Can use dispersant, for example non-ionic dispersing agent forms high solids content suspension.Dispersant used may be identical or different with the optional dispersant using in grinding steps.But, rear grinding stage dispersant used is the flocculation in order to limit the particulate inorganic material in high solids content suspension and add and conventionally exist with dispersant effective dose, be generally at least about 0.1 % by weight of dry inorganic particles material, or at least about 5 % by weight.The amount of the dispersant that can exist can be at least about 0.3 % by weight of dry inorganic particles material be to about 1.5 % by weight.The amount of the dispersant of regulation is specially adapted to GCC and PCC.

When this inorganic particles material is during available from naturally occurring source, the material that some dirts may contamination grindings.For example, naturally occurring calcium carbonate is combined existence with other mineral.In some cases, also may comprise other mineral of a small amount of interpolation, for example, also can have one or more in kaolin, calcined kaolin, wollastonite, bauxite, talcum or mica.But generally speaking, in certain embodiments of the present invention, inorganic particles material used may contain and be less than 5 % by weight, is preferably less than other dirt of 1 % by weight.

PCC can be used as the source of the particulate calcium carbonate in the present invention, and can be by available any known method manufacture in this area.TAPPI Monograph Series No 30, " Paper Coating Pigments ", 34-35 page has been described three kinds of main business preparation methods that are applicable to the winnofil of preparing paper industrial goods, but also can be used for implementing certain embodiments of the present invention.In all three kinds of methods, first calcined limestone, to produce quick lime, then produces calcium hydroxide or milk of lime by quick lime in curing in water.In first method, milk of lime is directly used carbon dioxide carbonating.The advantage of this method is not form accessory substance, and relatively easily controls character and the purity of calcium carbonate product.In the second approach, make milk of lime contact to produce lime deposit and sodium hydroxide solution by double decomposition with soda ash.If this method is commercially attractive, NaOH be separated substantially completely with calcium carbonate.In the third primary commercial method, first milk of lime contact to produce calcium chloride solution and ammonia with ammonium chloride.Then make calcium chloride solution contact to produce winnofil and sodium chloride solution by double decomposition with soda ash.

PCC can be configured as cake (for example filter cake), and it comprises at least about 70 % by weight solid contents, and surplus is water.Dispersant (for example non-ionic dispersing agent or anionic dispersing agents) can be directly and this cake merge, and optionally before adding dispersant, add water in this cake.

The method of manufacturing PCC produces very pure calcium carbonate crystal and water.This crystal can be according to concrete reaction method used with various shape and size manufacture.Three kinds of principal modes of PCC crystal are aragonite, rhombohedron (rhombohedral) and scalenohedron (scalenohedral), and all these is applicable to certain embodiments of the present invention, comprises their mixture.

According to some embodiments, kaolin as herein described and calcium carbonate can be used as the pigment product in Paper or cardboard product coating as described herein.

According to some embodiment, the ratio of kaolin and calcium carbonate can be extremely approximately 80:20 of about 20:80, or extremely approximately 70:30 of about 30:70, or about 40:60 is to about 60:40.

According to some embodiments, coating composition for the manufacture of Paper or cardboard product and the coating on other base material can comprise the waterborne suspension of particulate pigment together with hydrophilic gel stick or adhesive, wherein particulate pigment can comprise kaolin and calcium carbonate, for example the combination of precipitation and/or grinding calcium carbonate (GCC).For example, the solid content of this paper coating composition can be greater than about 60 % by weight, and for example at least about 70% or high as far as possible, but still the composition of the adequate liquidity that can be used for coating is provided.According to some embodiments, this coating composition can comprise dispersant, for example, account for the polyeletrolyte of maximum about 2 % by weight of the pigment dry weight of existence.For example, polyacrylate and the copolymer containing polyacrylic acid ester units can be used as suitable polyeletrolyte.Can be alone for this coating composition according to the kaolin of some embodiments and calcium carbonate, or they can with one or more other known pigment, for example calcined kaolin, titanium dioxide, calcium sulfate, satin white, talcum use together with so-called " plastic pigment ".In the time using the mixture of pigment, can be present in this pigment composition with the amount of at least about 80% of the gross dry weight amount of hybrid pigment according to the kaolin of some embodiments and calcium carbonate pigment product.

According to some embodiments, the adhesive of this coating composition can comprise by originating available from known plants, and for example derivative adhesive of the native starch of wheat, corn, potato or cassava must use starch as adhesive ingredients although be not.Mention other adhesives below, they can with or do not use together with starch.

According to some embodiments, can be unmodified or raw starch as the starch of adhesive ingredients, or it can pass through one or more chemical treatment modifications.For example, can by starch oxidation with by it some-CH ₂oH groups converted one-tenth-COOH group.In some cases, this starch can have the acetyl group-COCH of small scale ₃.Or, can be by starch chemical treatment to be cationic or both sexes, particularly existing cationic charge, have again anionic charge.Also can be by using for example-O-CH ₂-CH ₂oH group ,-O-CH ₂-CH ₃group or-O-CH ₂-CH ₂-CH ₂starch is changed into starch ether or hydroxyalkylation starch by substitute-OH group of-OH group.Available another kind of chemically treated starch is starch phosphate.Or raw starch can be by diluted acid or enzyme hydrolysis to produce the colloid of dextrin type.

According to some embodiments, in this coating composition, the amount of amylum adhesive used can be extremely about 25 % by weight of about 4 % by weight of pigment dry weight.Amylum adhesive can with one or more other adhesives, the composite adhesives of for example latex or polyvinyl acetate or polyvinyl alcohol type uses together.When amylum adhesive and another adhesive, for example, when composite adhesives uses together, the amount of amylum adhesive can be extremely about 20 % by weight of about 2 % by weight based on dry colour weight, and the amount of composite adhesives can be extremely about 12 % by weight of about 2 % by weight based on dry colour weight.For example, at least about 50 % by weight of binder combination comprise modification or unmodified starch.

According to some embodiments, the using method of coating composition can comprise coating composition is applied on paper or cardboard and this Paper or cardboard of press polish to form gloss coating thereon.According to some embodiments, on the one or both sides of this Paper or cardboard, form gloss coating.According to some embodiments, press polish can comprise makes Coated Paper or cardboard from passing through one or many between calender nip (calender nips) or felt wrapped roll to improve Paper or cardboard smoothness and gloss and to reduce bulk.According to some embodiments, elastomer coated roller can be used for suppressing high solids content composition, and can apply the temperature of rising, and/or can be through overpressure zone five times or more times.

According to some embodiments, the Paper or cardboard after coating and press polish can have 30 grams/m to 70 grams/m, the unit are gross weight of for example 49 grams/m to 65 grams/m or 35 grams/m to 48 grams/m.Final coating can have preferably 3 grams/m to 20 grams/m, for example weight per unit area of 5 grams/m to 13 grams/m.Can on the two sides of paper, all apply this coating.According to some embodiments, paper glossiness can be greater than 45 TAPPI units, and the Parker Print Surf value of each paper and coating under 1 MPa pressure can be less than 1 micron.

Can be by the experimental measurement coated paper of formulating in TAPPI Standard No 480 ts-65 or the glossiness of paperboard surface.Measure the light intensity reflecting at a certain angle from Paper or cardboard surface and compare with the standard of known gloss value.Incident and folded light beam are all 75 degree angles with surface normal.Result is expressed as TAPPI glossiness unit.According to some embodiments, it is about 50 that the glossiness of pigment product can be greater than, for example, be greater than 55 TAPPI units.

Parker Print Surf test the tolerance of paper surface flatness is provided and comprise measure pressurized air under known proof force, be clipped in the top board that comprises compressed air outlet and upper surface according to the character of tested Paper or cardboard coated with the soft or hard speed with reference to leaking in the coating Paper or cardboard sample between the base plate of fid tablet.By air effusion speed, computation paper surface and with reference to cube gap of the cubic root in micron between material (root mean cube gap).Less this gap representative is subject to the surperficial high light slippery of test paper.

According to some embodiments, the adhesive of this coating composition or adhesive can be 4 % by weight to 30 % by weight of the solid content of this coating composition, for example 8 % by weight to 20 % by weight (for example 8 % by weight to 15 % by weight).Consumption depends on the type of coating composition and adhesive, and adhesive itself may comprise one or more compositions.For example, the hydrophilic gel stick that comprises one or more following adhesive or adhesive ingredients can use taking following ormal weight: (a) latex: content is as 4 % by weight to 20 % by weight (latex comprises for example styrene-butadiene, acrylic latex, vinyl acetate latex or styrene acrylic copolymer); (b) other adhesive: content is 4 % by weight to 20 % by weight.The example of other adhesive comprises casein, polyvinyl alcohol and polyvinyl acetate.

According to the type of coating composition and/or the material that will be coated with, in this coating composition, can comprise the additive of various kinds.The example of the optional additives of these kinds is as follows:

(a) crosslinking agent, maximum 5 % by weight of for example content (for example glyoxal class, melamine resin, zirconium carbonate ammonium);

(b) water retention aid, maximum 2 % by weight of for example content (for example sodium carboxymethylcellulose, hydroxyethylcellulose, PVA(polyvinyl acetate), starch, protein, polyacrylate, natural gum, alginate, polyacrylamide bentonite and other commercially available prod for this type of purposes sale);

(c) viscosity modifier or other thickener, maximum 2 % by weight of for example content (for example polyacrylate, emulsion copolymers, cdicynanmide, three alcohols, APEO, urea, sulfated castor oil, polyvinylpyrrolidone, montmorillonite, sodium alginate, xanthans, sodium metasilicate, acrylic copolymer, HMC(CMC), HEC(hydroxyethylcellulose));

(d) lubricated or calendering agent, maximum 2 % by weight of for example content (for example calcium stearate, ammonium stearate, zinc stearate, wax emulsion, wax, alkyl ketene dimer, glycol);

(e) dispersant, maximum 2 % by weight (for example polyeletrolytes of for example content, as polyacrylate/salt and the copolymer that contains polyacrylate/salt thing class, for example polyacrylate (for example sodium and aluminium salt, optionally have II family slaine), calgon, nonionic polyalcohol, polyphosphoric acid, condensed phosphoric acid sodium, non-ionic surface active agent, alkanolamine and be usually used in other reagent of this function);

(f) antifoaming agent/defoamer, maximum 1 % by weight of for example content (for example surfactant blend, tributyl phosphate, fatty polyoxyethylene ester+fatty alcohol, fatty acid soaps, silicone emulsion and other are containing the composition of silicone, wax in mineral oil and inorganic particles, emulsifying hydrocarbon blend and other compound of selling for implementing this function business);

(g) dry or wet adhere to (pick) improves additive, maximum 2 % by weight of for example content (for example melmac, polyethylene emulsion, urea aldehyde, melamino-formaldehyde, polyamide, calcium stearate, maleic anhydride of styrene etc.);

(h) dry or wet friction improvement and anti-wear additive, maximum 2 % by weight of for example content (for example glyoxal resin, oxidic polyethylene, melmac, urea aldehyde, melamino-formaldehyde, Tissuemat E, calcium stearate etc.);

(i) gloss ink is held and is stayed additive, maximum 2 % by weight of for example content (for example oxidic polyethylene class, polyethylene emulsion, wax, casein, guar gum, CMC, HMC, calcium stearate, ammonium stearate, sodium alginate etc.;

(j) optical brightener (OBA) and fluorescent whitening agent (FWA), maximum 1 % by weight of for example content (for example diphenyl ethylene derivatives));

(k) dyestuff, maximum 0.5 % by weight of for example content;

(l) antimicrobial/antiseptic, maximum 1 % by weight of for example content (for example metaborate, neopelex, rhodanate, organic sulfur, Sodium Benzoate and be other compound that this function is sold, the anti-microbial polymer series that for example Calgon Corporation sells);

(m) levelling and even flat auxiliary agent, maximum 2 % by weight of for example content (for example nonionic polyalcohol, polyethylene emulsion, aliphatic acid, ester and 01 derivatives, alcohol/oxirane, CMC sodium, HEC, alginate, calcium stearate and be other compound that this function is sold);

(n) lipotropism or anti-oil additive, maximum 2 % by weight of for example content (for example oxidic polyethylene class, latex, SMA(maleic anhydride of styrene), polyamide, wax, alginate, protein, CMC and HMC);

(o) water resistant additive, maximum 2 % by weight of for example content (for example oxidic polyethylene class, ketone resin, anionic latex, polyurethane, SMA, glyoxal, melmac, urea aldehyde, melamino-formaldehyde, polyamide, glyoxal class, stearate class and be other material that this function is sold); With

(p) insolubilizer, maximum 2 % by weight of for example content.

For all above-listed additives, the dry weight of the pigment of the percentage by weight providing based on existing in said composition.If additive exists with minimum flow, this minimum flow can be 0.01 % by weight based on pigment dry weight.

According to some embodiments, can be on sheet material forming machine (i.e. " at machine (on-machine) ") or on spreader or coating machine " outside machine (off-machine) " coated substrate.The use of high solids coatings composition may be desirable, because such composition often leaves less water to be evaporated after coating process.But solid content should not be high enough to cause high viscosity and levelling problem.

According to some embodiments, this coating process can comprise that (i) is applied to coating composition the instrument on the base material that will be coated with, for example applicator; (ii) guarantee the instrument of the coating composition that applies aequum, for example metering device.In excess coating material composition is applied to applicator time, can provide metering device in applicator downstream.Or, can for example, by metering device (being film press form) coating composition of correctly measuring be applied in applicator.In the time that coating applies and measure, can use the base material of backing roll (for example one or two applicator) supporting coating or what all need not (being web tension).The time (being the time of staying) that coating contacts with base material before finally removing excess coating material can be short, long or variable.

According to some embodiments, can add coating composition by dispense tip at coating station.According to required coating quality, this base material can single application, two coatings and three coatings.In the time that more than one coating is provided, primary coat (being precoated shet) can have more cheap formula and optionally in coating composition, have less pigment.According to the face number of each dispense tip coating, the coating machine that applies two coatings (having a coating on each of base material) can have two or four dispense tip.Once coating one side only of some dispense tips, but the two sides that some sized roller applicators (for example film press, door roller (gate roll), sizing applicator) can a coated substrate.

In step (b), the example of available coating machine comprises Kohler coater, knife type coater, rod coater, metering bar coater, bull coating machine, roll coater, roller/knife type coater, cast coater, laboratory coating machine, intaglio plate coating machine, kiss coater, liquid application system, reverse roll coater and extrusion coated machine.

According to some embodiments of coating composition as herein described, can add water in solid so that certain solid concentration to be provided, it,, in the time being applied on paper to required target coating weight, has the rheological characteristic that is applicable to for example, being coated with about 1 pressure to about 1.5 bar (scraper pressure) said composition.For example, solid content can be about 60% to about 70 % by weight.

Embodiment

In order to assess coating composition, use typical cardboard used in packaging industry as base material or base stock (base stock).Use CLC (Cylindrical Lab Coater) machine that the sample coating composition that contains selected tabular clay and carbonate pigment is applied on cardboard.In the one side of cardboard, apply sample coating composition and sample is coated with to twice (being base coating and overlay coating).Then test by the sample cardboard press polish of coating and in the enterprising line bend modulus of cardboard sample and the deflection of coating and press polish.Sample uses CreaseStream along the longitudinal and horizontal impression.After this, impression sample uses rubber rollers folding to simulate the impression in industry or manufacturing environment and to fold.

Examine under a microscope the fault occurring on impression and folding path, and obtain image to can evaluate peeling off and the vision grade of fracture area of folding line place.The correlation between vision grade and bending modulus and the deflection of tearing tendency is peeled off in assessment.

Assessment has the sample hydrous kaolin pigment of difformity factor, steepness and size distribution.Following table 1 shows the physical property of sample Kaolin pigments used in different tests as herein described.Use above-described technology to measure the form factor of Kaolin pigments sample.Use the size distribution of above-described Sedigraph commercial measurement Kaolin pigments sample.

Table 1.

Kaolin pigments sample and calcium carbonate pigment sample (being grinding calcium carbonate (GCC)) are merged, the pigment sample of merging with as test to each required solid content slurrying of mentioning in relevant table herein.In order to test, make base coating weight remain on 13 grams/m and make overlay coating weight remain on 10 grams/m.In given the test agent coating composition, also comprise following component: polyvinyl acetate based adhesive (available from Celanese Emulsions Resyn 1103); Acryloid cement (available from Rohm and Haas Rhoplex P-308); Carboxymethyl cellulose (CMC) thickener (available from METSA Specialty Chemicals FINNFIX 30); Carboxymethyl cellulose (CMC) thickener (available from Noviant FINNFIX 10); Alkali swellability emulsion (HASE) thickener of hydrophobically modified (available from Rohm and Haas Rhoplex RM232D); Acrylic emulsion copolymers thickener (available from Alco Chemical Alcogum L29); And coating lubricant (available from Bercen, the Berchem 4095 of Inc.).

experimental technique

In order to assess the feature of peeling off and ftracture of sample, coating and test cardboard sample.Coated board uses the press polish under 175 pounds/square inch of (psi) pressure, 150 ℉ of Beloit Model 750 calenders.Coated sample is kept at least 24 hours in TAPPI conditioning chamber, after this use CreaseStream machine impression.Longitudinally and laterally impression of sample, after this at coated face first dorsad, then folding in the direction of coated face, to obtain the visually significant difference of the crackle occurring in folding region.Use 500 grams of rubber rollers to manufacture folding line.After this sample is shakeout, and use microscope to obtain to ftracture-peel off the image of tendency.

8 to 10 people's of training team is used vision grading method assessment cracking and peels off result, and grade 1 is best, and class 5 is common, and grade 10 is the poorest.To this team provide relevant to each grade point with reference to image so that given the test agent and these are compared with reference to image, thereby obtain result more accurately by vision grading method.Report the average cracking of each given the test agent and peel off grade.

For cracking and the visual assessment that peels off tendency are considered following factors, for cracking: the overall size of (1) crackle; (2) crack length; (3) crack number; For peeling off: the coating block of (1) disappearance; (2) the loose coating particles of staying folding region; (3) by the coating of peeling off from folding region.

In order to assess the intensity with the sample cardboard of tested coating sample coating, according to roof control test sample, each sample supports in opposite ends, and the mid point between fulcrum applies load.Referring to Fig. 1, it shows the schematic diagram of test arrangement, and wherein P is the load that is applied to sample center, and L is sample length, and E is elastic modelling quantity, and I is the moment of inertia and is deflection.

On coated board, carry out resistance to bending measurement according to ASTM D790-B method.Use with the Thwing Albert EJA series instrument of 10N dynamometer and MAP-Motion Analysis Presentation software and collect initial data.Can understand by bend test result the intensity of tested material.Use Thwing Albert instrument record to be applied to capacity value on sample and the initial data of related variation.Deflection is calculated and is considered that load in the initial segment of load-displacement curve figure and displacement readings are to distinguish better sample.Power is applied on each sample in x-y plane.In elastic range, can observe, load and displacement relation are linear.Along with start crack initiation in this region, this initiation region is tell-tale.

In test process, cross over two support aluminium anvils and place each sample.Point out, before carrying out bend test, sample cardboard is coated with on CLC, and press polish also regulates.Apply power at each sample center, and record the repellence of each sample to the bending force applying.Each sample kept at least 24 hours before carrying out bend test in TAPPI conditioning chamber.Each sample has the size of 3 inches of 1 inch of x.

Whether the better destruction of making great efforts research pigment packed structures can reduce modulus or the deflection of sample.The impact of the different GCC roughness of research in coating on engineering properties and on peeling off and the impact of tearing tendency.Following table 2 shows the formulation for coating material that this test comprises.Use Precision coating machine on Mylar film, to carry out coating blade coating (drawdowns).Use the RL003 Polish MT/DF Mylar drawing that Grafix manufactures to use film (drafting film) as the base material in this experiment.

Table 2.

Fig. 2 shows the clay with 50:50: when the blend of carbonate ratio, the exemplary of the tabular clay of high form factor (as CKS2 and CKS1) shows than modulus low together with CGCC1 together with GCC1.These results are studied based on laboratory scale blade coating, but the significant difference of modulus result between master curve figure show sample.Based on these results, use CLC machine to carry out further test and apply process and the checking flexing resistance of GCC roughness on cardboard and the impact of folding ability of mind with simulate commercial.

Test improve amount of thickener in coating composition on peel off with the impact of tearing tendency with measure whether can improve overlay coating hold the property stayed (hold out) to can permeate the more open base coating of enhancing by overlay coating.The details of tested coating composition is provided in following table 3.

Table 3.

Comparative result, observes peeling off with tearing tendency than more serious in longitudinally in laterally.Also find, improve cracking in having reduced longitudinally of RM232 amount of thickener and peel off seriousness.Relatively these two kinds of CMC types, the CMC(Finnfix 30 of higher molecular weight) the slightly improved result of peeling off and ftracture is provided.

To the work of many sample test coating compositions in order to the modulus of determination influences coating composition and the factor of deflection.The mechanical intensive property of the cardboard that research is only coated with the cardboard of base coating coating with overlay coating and base coating is to measure single and double coating to peeling off and the response of tearing tendency.Following table 4 shows different pigment blend used in this test and other composition details.

Table 4.

As shown in Figure 3, compared with comprising the base coating composition of Carbital 60, in the situation of base coating composition that comprises GCC1, modulus reduces slightly.The bending break stiffness (IE) of the coating that as shown in Figure 4, contains GCC1 is a little less than the bending break stiffness of the coating that contains CGCC1.The base coating composition that comprises GCC1 and KS1 under lower latex content provides lower deflection result.Fig. 5 shows, provides a little less than the flexural modulus values of coating composition base coating that comprises Carbital 60:CKS1 with the coating composition that comprises Carbital 70:CKS1 as the cardboard of base coating coating.The deflection value of the cardboard being coated with the coating composition base coating that comprises GCC1:CKS1 as shown in Figure 6, is a little less than the coating composition base coating that comprises CGCC1:CKS1.

Fig. 7 and 8 the fixed coating composition of horizontal legend middle finger are enumerated to the order of the high-modulus (the high latex overlay coating/CGCC1:CKS of CGCC4:Kao91 30:70 base coating) in the lower right corner with the minimum bending modulus (CGCC4 overlay coating/GCC1/CKS2 base coating) in the upper left corner.Show peeling off and tearing tendency of coated board with respect to flexural modulus results.Although the data point in Fig. 7 and 8 is disperseed, between the base coating composition that contains GCC1 and CGCC1, there is obviously difference.In general, the base coating composition that contains GCC1 tends to reduce the seriousness of peeling off and ftractureing.Higher latex content in overlay coating composition seems to improve peels off and cracking performance.But base coating composition is stronger than overlay coating composition on the impact of peeling off and ftracture.

In addition, test different base coating compositions and whether can reduce adhesive still reducing in peeling off with assessment.The selection of base coating pigment is based on test result mentioned above.Coated board on CLC, carries out standard paper test, and evaluation is peeled off and tearing tendency grade.

Test following pigment sample with regard to the folding ability of mind of coated board: (1) KS1; (2) CKS2; (3) CKS1; (4) CGCC1; (5) GCC1.Test following variable with regard to the folding ability of mind of coated board: thickener variation, KOH dispersion, coating weight variation, binder content (PVAc, 22,19 and 16 parts), PVAc+ acrylic acid (11 and 11 parts) and adhesive type (PVAc and PVAc+ acrylic acid).Result shown in following table 5 is used constant coating weight and actual amount of thickener normalization for generalized regression.

?	Component	BC17	TC
				Pigment	CKS2	50	?
?	GCC1	50	?
				?	CGCC4	?	70
?	CKS3	?	30
				Adhesive	PVAc 1103	16	11
?	BASF P308	?	11
				Lubricant	Berchem 4095	?	0.7
Thickener	Alcogum L29	0.34	0.12

Table 5.

Fig. 9 shows, can realize lower peeling off and tearing tendency in base coating composition under the amount of thickener improving.The experiment of carrying out before (wherein improving the amount of thickener in overlay coating composition) is observed to similar results.As shown in Figure 10, along with the raising of amount of thickener, peeling off and tearing tendency of the reduction observed under higher amount of thickener explained in slightly reducing of bending break stiffness value.

With reference to Figure 11 and 12, although some data points are disperseed, Trendline shows along with base coating weight improves, the grade raising of peeling off and ftracture.Therefore, can regulate base coating weight level to realize peeling off and the required impact of tearing tendency.

As shown in Figure 13, pigment blend GCC1/KS1 and CGCC1/KS1+PVAc1103: acrylic acid P308 adhesive and the CGCC1/CKS1 composition+PVAc1103 contrasting: acrylic acid P308 adhesive is compared and shown lower bending modulus and peel off tendency.The result of peeling off of GCC1/CKS2 composition is also better than contrasting CGCC1/CKS2.

As shown in Figure 14, formula GCC1/KS1 and CGCC1/KS1+PVAc1103: acrylic acid P308(11+11 part) adhesive compares with the CGCC1/CKS1 contrasting and shows lower flexural modulus values and improved tearing tendency.From Figure 14, can observe, a little less than the correlation between bending modulus and cracking performance.

As shown in Figure 15, GCC1/KS1 and CGCC1/KS1+PVAc1103: acrylic acid P308(11+11 part) adhesive bending break stiffness result lower than tester and have than reference composition CGCC1/CKS1 good peel off tendency.

A little less than Figure 16 shows the correlation between tearing tendency and bending break stiffness.But, coating composition GCC1/KS1 and CGCC1/KS1+PVAc1103: acrylic acid P308(11+11 part) and adhesive shows the consistent improvement of tearing tendency under lower deflection.

The result of on average peeling off and ftracture, bending modulus and the deflection measurement result of following table 6 show sample coating compositions.

Table 6.

Following table 7 shows improves peeling off and the sample coating composition of cracking performance of cardboard compared with reference composition separately.

Table 7.

Based on test, comprise that the sample coating composition of CGCC1/KS1 and GCC1/KS1 provides than low the peeling off and tearing tendency of the reference composition that comprises CGCC1/CKS1.The bending modulus of these samples and deflection result are starkly lower than the sample with reference composition CGCC1/CKS1 coating.The peeling off with tearing tendency result of sample composition that comprises GCC1/CKS2 is better than reference composition CGCC1/CKS2.The carbonate only changing in contrast coating composition CGCC1/CKS2 shows the remarkable improvement of peeling off with tearing tendency.

As shown in result of the test, GCC roughness seems to affect modulus and the deflection of coating.The arrangement of the packed structures in coating and the tabular clay of high form factor has strong impact to the in-plane strength character of coating.In base coating, GCC1 improves with the combination of clay the result of peeling off and ftracture compared with the base coating composition that contains CGCC1.The composition that contains KS1 under lower latex content in base coating provides improved result compared with comprising the base coating of CKS1 in some cases.Can use slightly high latex amount improve cracking and peel off tendency.The composition that comprises KS1 pigment at base coating composition can improve folding ability of mind under the binder content normally or slightly reducing.Test and also show, amount of thickener provides the improved foldable integral ability of paper grades a little more than the coating composition of normal contents.

According to some embodiments, coating composition can comprise the kaolin with the form factor that is less than about 70 and the particle mean size (d with at least about 2.4 microns ₅₀) and the calcium carbonate of at least about 30 steepness coefficient.For example, d ₅₀can be greater than about 2.6 microns, be greater than about 2.8 microns, or be greater than about 3.0 microns.According to some embodiments, steepness coefficient (for example d ₃₀/ d ₇₀x100) can be greater than approximately 32, be greater than approximately 34, be greater than approximately 36, be greater than approximately 40, or be greater than about 43.Some embodiments of this coating can contain the grinding calcium carbonate of the exemplary particle size distribution having shown in following table 8.Composition in table 8 is known as " GCC2 "

Sedigraph 5100	GCC2 composition
		< 10 microns (%)	98 % by weight
< 5 microns (%)	81 % by weight
		< 2 microns (%)	40 % by weight
< 1 micron (%)	13 % by weight
		< 0.5 micron (%)	2 % by weight
< 0.25 micron (%)	1 % by weight
		d 30	1.7 micron
d 50	2.6 micron
		d 70	4.0 micron
Steepness coefficient	43
		BET surface area	3 m 2/g

Table 8.

As can be seen from Table 8, the median particle (d of GCC2 ₅₀) relatively large, be about 2.6 microns.The overall particle size of GCC2 has at least about 30, especially about 43 relatively high steepness coefficient.GCC2 classification, to remove the thickest particle, so that esd is less than the percentage of particle of about 10 microns is larger, is still kept to roughly thick size distribution simultaneously.Also for example, indicate this overall coarseness to distribute by relatively low particulate (particle that esd is less than 1 micron) percentage.

When being used in coating, as in base coating time, bending break stiffness and the folding ability of mind of the thicker narrow GCC size distribution in GCC2 on double-deck coated paper and cardboard has remarkable impact.As shown in table 9 and 10, by with 50:50(table 9) with 25:75(table 10) different tabular clay and the GCC2 of clay/carbonate ratio blend, prepare several formulation for coating material.In the time being placed on base material, assess smoothness and the folding property of blend clay-carbonate based priming coat.Also the pure coating that assessment has 100%CGCC1, GCC2 and CKS2 is with assessment coating structure, bending break stiffness and the impact on folding ability of mind thereof.

As mentioned above, adhesive and amount of thickener may affect the folding ability of mind of coated substrate.Therefore,, in the time of assessment clay-GCC2 composition, it is constant that the adhesive of base coating and amount of thickener keep.It is constant that overlay coating formula also keeps.In order to assess this clay-GCC2 composition, twice coated SBS base plate on CLC machine.All coating is prepared under best solid content and about 8.5 pH.In order to test, base coating weight is held constant at 13 grams/m, and overlay coating is held constant at 10 grams/m.All samples is press polish before test.

Table 9

Table 10.

The folding property grade of each clay-GCC2 composition is compared in Figure 17 demonstration with two kinds of reference composition with CGCC1, CKS2.As shown in Figure 17, compared with other blend of testing in above-mentioned a series of experiments without GCC2, the compositions table that contains GCC2 pigment in base coating reveals improved sample folding property.Except the KS4/GCC2 and KS3/GCC2 composition of 50:50 ratio, all other blends for example all show, than the improved folding ability of mind of contrast coating (Cntrl CKS2/CGCC1 and Cntrl CKS1/CGCC1).The improved folding grade that these formulation for coating material obtain is in 1 to 5 scope, and conventionally in 1 to 4 scope.

As shown in Figure 17, containing 50:50 and the KS1/GCC2 of 25:75 ratio and the base coating blend of the CKS1/GCC2 of 25:75 ratio compares with control formula and shows improved folding property and smoothness with 100% GCC2.Compared with 100% GCC2 blend, some blends, the remarkable improvement that also shows smoothness as the CKS1/GCC2 of 50:50 ratio, and other blends, as the CKS2/GCC2 of 50:50 ratio shows the slight improvement of smoothness, keep suitable folding property simultaneously.Although the CKS2/GCC2 blend of 25:75 ratio seems not show any remarkable improvement of smoothness compared with 100% GCC2 blend, show best folding property result compared with all the other blends of this blend and this group.

The bending break stiffness result of the coating described in Figure 18 display list 9 and 10 is wherein used 100% CGCC1 in base coating formula.Bending break stiffness result in Figure 18 shows the bending break stiffness of other clay-carbonate blend object height for example, comprising with the sample comparison experiment of KS1/GCC2 blend (50:50 and 25:75 ratio) coating.Not bound by theory, but the bulky structure of the coating blend that contains KS1 pigment contributes to the slightly high bending break stiffness of these blends.Relatively deflection result and the above results (for example Fig. 4 and 6) of Figure 18, the overall range of the deflection value of tabular clay-GCC2 form seems a little less than tabular clay-CGCC1 blend.

Figure 19 shows the comparison of the bulk of above-mentioned tabular clay-carbonate blend in the situation that of CGCC1 and GCC2.Figure 19 shows that KS1/ carbonate blend tends to produce than the more structure of bulky of other clay-carbonate blend under 50:50 & 75:25 ratio.From Figure 19, also find out, 100% GCC2 with thicker carbonate pigment produces than the more structure of bulky of 100% CGCC1.Standard GCC, as contain the higher CGCC1 that is for example less than the particulate percentage of 2 microns and can provide than the narrower size distribution with thicker pigment, accumulation as closeer in GCC2.The bulky character of the blend that similarly, contains KS1 can be used for hiding the uneven of base paper and realizes improved smoothness and light scattering.

Figure 17-19 show, KS1/GCC2 blend composition can provide improved folding ability of mind and the required best packed structures of mechanical intensive property.For example, the formula that contains KS1 in base coating shows improved folding property result in disclosed each experimental result in this article all the time.Find out from the result described in Figure 17-19, the KS1 of being combined with GCC2 provides improved smoothness and folding property and does not affect the bending break stiffness of coated sample.

Conventionally, with the tabular clay pigment of KS2, CKS2, CKS1 and KS1 of GCC2 blend seem to show than with the improved smoothness of identical tabular clay pigment and the folding property of CGCC1 blend.Change base coating formula into smoothness that 100% GCC2 also seems to improve coating from 100% CGCC1, but may damage to a certain extent folding property.It is also important that and point out, compared with control formula, 100% GCC2 coating shows the folding property of raising and suitable smoothness.

The mercury porosity of test sample coated paper base material.Figure 20 shows the mercury porosity result of coated paper base material.Mercury injection method is the widely used technology for characterizing pore-size distribution and pore volume measurement result.The nonwetting paper of mercury surface.In this test method, make mercury invade sample by improve pressure in separate stage.The volume of invading the mercury of pore structure is associated with pore volume and pore-size distribution.

As shown in Figure 20, different clay-carbonate pigments of selecting according to their different physical properties produce visibly different coating structure.Total pore volume result of invading depends on (sometimes clearly) base coating pigment blend.Some embodiments draw 0.4 to 0.6 cubic centimetre of/gram (cm ³/ g), for example 0.4 to 0.41 cm ³/ g, 0.41 to 0.42 cm ³/ g, 0.42 to 0.43 cm ³/ g, 0.43 to 0.44 cm ³/ g, 0.44 to 0.45 cm ³/ g, 0.45 to 0.46 cm ³/ g, 0.46 to 0.47 cm ³/ g, 0.47 to 0.48 cm ³/ g, 0.48 to 0.49 cm ³/ g, 0.49 to 0.50 cm ³/ g, 0.50 to 0.51 cm ³/ g, 0.51 to 0.52 cm ³/ g, 0.52 to 0.53 cm ³/ g, 0.53 to 0.54 cm ³/ g, 0.54 to 0.55 cm ³/ g, 0.55 to 0.56 cm ³/ g, 0.56 to 0.57 cm ³/ g, 0.57 to 0.58 cm ³/ g, 0.58 to 0.59 cm ³/ g or 0.59 to 0.60 cm ³the pore volume of/g.

Coating porosity structure depends primarily on base coating formula.Total volume result of invading shows the coating structure difference being caused by base coating blend.Figure 20 shows, the thicker carbonate pigment of narrow size distribution in base coating, as GCC2 brings larger structuring ability.By substitute CGCC1 with GCC2 in base coating, obtain higher pore volume.The overall raising of pore volume is of value to peeling off and tearing tendency of reduction coating.Mercury injection method result is also associated with the bulk result of reporting in Figure 19.Although do not wish to be subject to theory, what seem to have higher pore volume may tend to be reduced in compared with bulky coating structure the stress being applied by coating in bending or folding operation process.Therefore, result shows to regulate base coating to fill a prescription to realize required coating structure and folding ability of mind.

After considering the explanation and practice of embodiment disclosed herein, other embodiment is apparent to those skilled in the art.Description and embodiment are only regarded as exemplary.

Claims (42)

1. a coating composition, it comprises:

There is the kaolin of the form factor that is less than about 70; With

Calcium carbonate, is wherein less than about 90 % by weight and has the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

2. the composition of claim 2, it further comprises thickener.

3. the composition of claim 2, wherein said thickener is to exist by described composition active material dry weight about 0.1% to about 0.9% amount.

4. the composition of claim 2, wherein said thickener is to exist by described composition active material dry weight about 0.2% to about 0.6% amount.

5. the composition of claim 2, wherein said thickener is to exist by described composition active material dry weight about 0.4% to about 0.9% amount.

6. the composition of claim 2, wherein said thickener is selected from alkali-soluble emulsion polyacrylic ester thickener and the CMC(carboxymethyl cellulose of alkali-soluble emulsion polyacrylic ester thickener, hydrophobically modified) thickener.

7. the composition of claim 1, the kaolin that is wherein less than about 30 % by weight has the esd that is less than about 0.25 micron.

8. the composition of claim 1, the kaolin that is wherein less than about 25 % by weight has the esd that is less than about 0.25 micron.

9. the composition of claim 1, the kaolin that is wherein less than about 20 % by weight has the esd that is less than about 0.25 micron.

10. the composition of claim 1, wherein said kaolin has the d that is less than about 1 micron ₅₀.

The composition of 11. claims 1, the kaolin that is wherein less than about 80 % by weight has the esd that is less than about 1 micron.

The composition of 12. claims 1, the kaolin that is wherein less than about 90 % by weight has the esd that is less than about 2 microns.

The composition of 13. claims 1, is wherein less than about 80 % by weight and has the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

The composition of 14. claims 1, is wherein less than about 70 % by weight and has the esd that is less than 2 microns more than the calcium carbonate granule of about 60 % by weight.

The composition of 15. claims 1, wherein said coating composition is paper substrates coating composition.

The composition of 16. claims 1, wherein said coating composition is cardboard substrate coating composition.

17. 1 kinds of paper products, the coating composition that it comprises claim 1 at least one surface of described paper product.

18. 1 kinds of board products, the coating composition that it comprises claim 1 at least one surface of described board product.

19. 1 kinds of coating compositions, it comprises:

There is the kaolin of the form factor that is less than about 70; With

There is the d of at least about 2.4 microns ₅₀the calcium carbonate of at least about 30 steepness coefficient.

The composition of 20. claims 19, it further comprises thickener.

The composition of 21. claims 20, wherein said thickener is to exist by described composition active material dry weight about 0.1% to about 0.9% amount.

The composition of 22. claims 20, wherein said thickener is to exist by described composition active material dry weight about 0.2% to about 0.6% amount.

The composition of 23. claims 20, wherein said thickener is to exist by described composition active material dry weight about 0.4% to about 0.9% amount.

The composition of 24. claims 20, wherein said thickener is selected from alkali-soluble emulsion polyacrylic ester thickener and the CMC(carboxymethyl cellulose of alkali-soluble emulsion polyacrylic ester thickener, hydrophobically modified) thickener.

The composition of 25. claims 19, the kaolin that is wherein less than about 30 % by weight has the esd that is less than about 0.25 micron.

The composition of 26. claims 19, the kaolin that is wherein less than about 25 % by weight has the esd that is less than about 0.25 micron.

The composition of 27. claims 19, the kaolin that is wherein less than about 20 % by weight has the esd that is less than about 0.25 micron.

The composition of 28. claims 19, wherein said kaolin has the d that is less than about 1 micron ₅₀.

The composition of 29. claims 19, the kaolin that is wherein less than about 80 % by weight has the esd that is less than about 1 micron.

The composition of 30. claims 19, the kaolin that is wherein less than about 90 % by weight has the esd that is less than about 2 microns.

The composition of 31. claims 19, wherein said calcium carbonate has the d of at least about 2.6 microns ₅₀.

The composition of 32. claims 19, wherein said calcium carbonate has the d of at least about 2.8 microns ₅₀.

The composition of 33. claims 19, wherein said calcium carbonate has the d of at least about 3.0 microns ₅₀.

The composition of 34. claims 19, wherein said calcium carbonate has at least about 32 steepness coefficient.

The composition of 35. claims 19, wherein said calcium carbonate has at least about 34 steepness coefficient.

The composition of 36. claims 19, wherein said calcium carbonate has at least about 36 steepness coefficient.

The composition of 37. claims 19, wherein said calcium carbonate has at least about 40 steepness coefficient.

The composition of 38. claims 19, wherein said calcium carbonate has at least about 43 steepness coefficient.

The composition of 39. claims 19, wherein said coating composition is paper substrates coating composition.

The composition of 40. claims 19, wherein said coating composition is cardboard substrate coating composition.

41. 1 kinds of paper products, the coating composition that it comprises claim 19 at least one surface of described paper product.

42. 1 kinds of board products, the coating composition that it comprises claim 19 at least one surface of described board product.